Scientists Find Blood from Young Mice Can Slow Aging in Old Mice

Humans have always placed a creepy amount of emphasis on blood, with folk stories the world over telling of vampiric creatures that drain their victims’ lifeforce. As science has learned more about blood and the diseases that affect it, many have wondered if young, unadulterated blood could improve health. A new study reinforces this idea, suggesting that young blood really can have rejuvenating effects on the old—at least if you’re a mouse with a three-year lifespan.

Since the 19th century, scientists have experimented with parabiosis, a somewhat gruesome procedure in which two animals are stitched together to combine their circulatory systems. The evidence has been weakly supportive of improved health, but parabiosis is usually only maintained for about three weeks before the animals (usually mice) are separated. Researchers from Duke University have published a new study on long-term heterochronic parabiosis, which pairs a young mouse with an old one, finding that the extended procedure might slow aging by as much as 10%.

The study followed mice that had been sharing blood for much longer than in previous experiments. The team combined the circulatory systems of two-year-old mice with mice that were just four months old, and they kept them connected for 12 weeks. After that, the mice were disconnected and analyzed over two months to see what biological changes might have taken place.

Older mice that shared blood with younger ones showed activation of genes associated with longer lifespans, and the cellular age of organs like the liver was reduced. These changes persisted for months after the animals were separated. According to senior author James White, this is the first evidence that heterochronic parabiosis can actually slow aging.

This news will no doubt pique the interest of humans who already have weird ideas about young blood. Some of the ultra-wealthy are known to receive transfusions from young donors on the assumption that it will slow aging. There are even startups that offer young blood transfusion services. The practice is so common in the California tech bubble that it was parodied in HBO’s Silicon Valley.

Credit: USAF / Public Domain

However, the team cautions that the mouse data doesn’t necessarily translate to humans. Mice only live for a few years, so attaching two of them for 12 weeks is a significant part of their total lifespans. It would be like stitching an 18-year-old human to a 50-year-old for eight years. Maybe that would grant a similar boost to the one seen in the study, but it’s wildly impractical and unethical.

We don’t yet know what blood factors produce enhanced longevity in heterochronic parabiosis, but it might be possible to figure out with more studies like this one. In the meantime, eccentric billionaires will continue injecting themselves with young blood for (probably) no benefit.